Though you may not have heard of biochar, it's a good bet you'd recognize it if you saw it.
Biochar is just charcoal. It's created when organic matter like wood chips, rice stalks or even manure is heated up in the absence of oxygen. Think of a sealed metal drum full of wood chips over a fire. It's simple, can be produced anywhere and could just end up saving the world.
For something as simple as charcoal, biochar — in the right applications — does three pretty amazing things: It takes carbon dioxide out of the atmosphere and locks it into a solid form, improves the health of soil it's plowed into, and creates clean energy, according to the International Biochar Initiative.
When organic matter is turned into biochar, the CO2 contained within the plant is converted into solid carbon. Plowing biochar into soil sequesters the carbon for a long time — biochar fields have been found in South America dating back thousands of years and still full of their carbon solids. Soils augmented with biochar retain nutrients better as the tiny, sponge-like structure of the carbon solids sucks up and holds the fertilizer, reducing the amount needed. The same structure holds water better and has been shown to decrease the emissions of nitrous oxide and methane into the air from the soil.
When former slash-and-burn farmers in the rainforests of South America adopt slash-and-char techniques, they're able to stay and farm the same plot of land year after year instead of having to move on every couple of seasons when the soil becomes depleted. Their path through the rainforest is halted, saving countless acres. The farmers are able to produce a lot more food on the healthier soil and can improve and invest in their land and infrastructure.
An easy sell
Wood waste can be converted into biochar, which can be added to soil to improve its health. (Photo: U.S. Department of Agriculture [CC0]/Flickr)
When organic matter is heated up in the absence of oxygen, it releases hot gases that can be captured and burned in power generators, or also refined into bio-oil and synthetic gas, both which can be further refined into effective gasoline and diesel substitutes. If the gases are burned right away, the process of creating biochar — called pyrolysis — is energy-positive, returning six to nine times as much energy as necessary to run and maintain it.
Right now we're far from squeezing out all the benefits biochar offers. Sustenance-based slash-and-burn farmers still must switch to slash-and-char, and we need to build the infrastructure for taking in agricultural waste from farms and then distributing the resulting biochar back to their fields. One of the great things about biochar is how easy it is to make. Poor farmers can make it using simple, handmade clay kilns, while rich farmers can build elaborate biochar processing plants that also generate electricity, bio-oil and synthetic gas.
Biochar is an easy sell. Everyone involved in the process wins. Poor farmers get more food for their work and are able to settle on one plot of ever-productive soil. Rich farmers and corporate agriculture save a lot of money on fertilizer and also see the same boost in production. The environment benefits because of the reduction in fertilizer runoff and the removal of CO2 from the air. Big business wins because of the profits generated from the production and distribution of biochar. Politicians get to take credit for implementing a pragmatic, job-creating solution to global warming. Workers get jobs. Governments get tax revenue.
Regrowing the rainforests
Researchers recently found that using biochar is an inexpensive and effective method to help tree seedlings survive during reforestation attempts in the Amazon rainforest. In areas mined for gold, the soil and the trees are harmed, making it difficult to regrow and nurture new trees to replace those that are lost.
Researchers from Wake Forest University’s Center for Amazonian Scientific Innovation (CINCIA) found that using biochar plus fertilizer improved the height and diameter of tree seedlings and also increased the number of leaves that the new seedlings were able to grow.
“The most difficult period in a tree seedling’s life is the first few months after transplanting,” study co-author Miles Silman, CINCIA associate director of science and Wake Forest’s Andrew Sabin Presidential Chair of Conservation Biology, said in a news release.
“But just a little bit of biochar does wonderful things to the soil, and it really shines when you add organic fertilizer.”
The study, which was published in the journal Forests, was based on research conducted in an Amazon region called Madre de Dios, the center of illegal gold mining trade in Peru.
This video above was produced by CINCIA for its Spanish-language outreach efforts to show how biochar is made from substances like Brazil nut husks, cocoa shells and sawdust.
“These are the kinds of landscapes we have to recover, and we are still trying to determine how to grow plants in them,” Silman said. “This soil is extremely limiting for natural regrowth, but treating them with biochar turns it into something that plants can grow in. That’s good for biodiversity and good for the people that have to make a living from the land.”
Editor's note: This story has been updated with new information since it was published in July 2009.